Here is the full list of all 58 Horace achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Find all the alternate title screen skins.
Push all the rubber ducks into the water in the Laundry Room.
Complete the game.
Buy all possible shop items..
Get the kids blamed for shop lifting.
Don't save the Man in Black.
Die 1000 times.
Win The One Tournament.
Defeat the helicopter boss.
Travel to the secret moon base.
Defeat the Ether boss.
Defeat the Water boss.
Find a secret room in the mansion.
Defeat the Fire boss.
Defeat the Earth boss.
Run the BASIC program everybody knows and loves...
Catch 200 objects.
Defeat the Air boss.
Find an alternate title screen skin.
Read 15 teletext pages.
Score 100 baskets in total.
Reunite with Heather and the Old Lady.
Kidnap Mr Deck from the TV Studio.
Get the high score on all the arcade games.
Earn £10000 from jobs, junk yards and other winnings.
Buy an item from a shop.
Meet up with Alice and Sim.
Go on a most excellent adventure with the Professor.
Clean 100000 things.
Take your first train ride.
Watch a train arrive and leave at any station.
Help to make bricks.
Earn £1000 from jobs, junk yards and other winnings.
Help to sort the post.
Earn £100 from jobs, junk yards and other winnings.
Play an arcade game.
Help to wash dishes.
Spring Logan from prison.
Empty 10 bins.
Learn to play the drums.
Defeat the Nanobot Boss.
Defeat the K-Bot 100 Boss.
Use the Atlas Gloves to tidy up the village hall.
Of dead Old Men?
Rescue the family from the burning house.
Return the blind man's cat.
Clean 10000 things.
Venture out of the mansion.
Climb walls with the Shoees for the first time.
Clean 1000 things.
Clean up your first thing.
Completed basic robot training.
Complete all other achievements.
Save the Man in Black.
Reach the end of the game having cleaned one million things.
Clean 1000000 things.
Find all the secret rooms in the mansion.
Complete the auto map by visiting every room in the mansion.